package com.coai.twin.engine

import com.coai.twin.tracking.BusinessEvent
import com.coai.twin.tracking.EntityType
import kotlinx.coroutines.flow.Flow
import org.springframework.stereotype.Service
import java.time.Duration
import java.time.Instant
import java.util.UUID

/**
 * 数字孪生引擎
 */
/**
 * 数字孪生引擎
 * 
 * 核心功能：
 * - 创建和管理业务实体的数字孪生体
 * - 实时状态同步
 * - 业务场景模拟
 * - What-If分析
 * 
 * @property stateManager 状态管理器
 * @property simulationEngine 模拟引擎
 */
@Service
class DigitalTwinEngine(
    private val stateManager: StateManager,
    private val simulationEngine: SimulationEngine
) {
    
    /**
     * 创建数字孪生体
     */
    /**
     * 创建数字孪生体
     * 
     * 为指定的业务实体创建一个数字孪生体，用于实时跟踪和分析
     * 
     * @param entityId 实体ID
     * @param entityType 实体类型（订单/产品/库存等）
     * @param config 孪生体配置
     * @return 创建的数字孪生体
     */
    suspend fun createTwin(
        entityId: String,
        entityType: EntityType,
        config: TwinConfiguration
    ): DigitalTwin {
        val initialState = loadCurrentState(entityId, entityType)
        
        val twin = DigitalTwin(
            id = UUID.randomUUID().toString(),
            entityId = entityId,
            entityType = entityType,
            state = initialState,
            config = config,
            createdAt = Instant.now()
        )
        
        // 启动实时同步
        startRealtimeSync(twin)
        
        return twin
    }
    
    /**
     * 同步物理实体到数字孪生
     */
    suspend fun syncPhysicalToDigital(event: BusinessEvent) {
        val twin = getTwinByEntityId(event.entityId) ?: return
        
        // 更新孪生体状态
        val newState = stateManager.updateState(twin.state, event)
        twin.state = newState
        
        // 触发内部模拟
        val simulationResult = simulationEngine.simulate(twin, event)
        
        // 更新可视化
        updateVisualization(twin, newState)
    }
    
    /**
     * 运行业务模拟
     */
    /**
     * 运行业务场景模拟
     * 
     * 基于指定的场景参数进行业务模拟，预测未来状态
     * 
     * @param scenario 模拟场景配置
     * @return 模拟结果，包含时间线和指标分析
     */
    suspend fun runSimulation(scenario: SimulationScenario): SimulationResult {
        val environment = createSimulationEnvironment(scenario)
        var currentState = loadInitialState(scenario)
        val timeline = mutableListOf<SimulationSnapshot>()
        
        var currentTime = scenario.startTime
        
        while (currentTime < scenario.endTime) {
            // 执行一个时间步长
            val stepResult = simulationEngine.step(
                environment = environment,
                currentState = currentState,
                deltaTime = scenario.timeStep
            )
            
            currentState = stepResult.newState
            currentTime = currentTime.plus(scenario.timeStep)
            
            // 记录快照
            timeline.add(SimulationSnapshot(
                time = currentTime,
                state = currentState.copy(),
                metrics = calculateMetrics(currentState)
            ))
            
            // 检查终止条件
            if (scenario.shouldTerminate(currentState)) {
                break
            }
        }
        
        val analysis = analyzeSimulation(timeline)
        
        return SimulationResult(
            scenario = scenario,
            timeline = timeline,
            analysis = analysis
        )
    }
    
    /**
     * What-If 分析
     */
    suspend fun runWhatIfAnalysis(
        baseScenario: SimulationScenario,
        variations: List<ScenarioVariation>
    ): WhatIfAnalysisResult {
        val baseResult = runSimulation(baseScenario)
        
        val variationResults = variations.map { variation ->
            val modifiedScenario = applyVariation(baseScenario, variation)
            val result = runSimulation(modifiedScenario)
            VariationResult(variation, result)
        }
        
        val comparison = compareScenarios(baseResult, variationResults)
        
        return WhatIfAnalysisResult(
            baseline = baseResult,
            variations = variationResults,
            comparison = comparison
        )
    }
    
    // 辅助方法
    private fun loadCurrentState(entityId: String, entityType: EntityType): TwinState {
        // 从数据库加载当前状态
        return try {
            // TODO: 实际应该从 MongoDB 或 Redis 加载
            val properties = mapOf(
                "entityId" to entityId,
                "entityType" to entityType.name,
                "status" to "ACTIVE",
                "lastUpdated" to Instant.now().toString()
            )
            
            val metrics = mapOf(
                "uptime" to 99.9,
                "throughput" to 1000.0,
                "errorRate" to 0.01
            )
            
            TwinState(properties, metrics)
        } catch (e: Exception) {
            logger.error("Failed to load state for $entityId", e)
            TwinState(emptyMap(), emptyMap())
        }
    }
    
    private fun getTwinByEntityId(entityId: String): DigitalTwin? {
        // 从缓存或数据库获取孪生体
        return try {
            // TODO: 实际应该从 Redis 缓存或 MongoDB 获取
            // 这里返回 null 表示未找到，需要创建新的孪生体
            null
        } catch (e: Exception) {
            logger.error("Failed to get twin for $entityId", e)
            null
        }
    }
    
    private fun startRealtimeSync(twin: DigitalTwin) {
        // 启动WebSocket或Kafka监听
        try {
            logger.info("Starting realtime sync for twin ${twin.id}")
            
            // TODO: 实际应该启动 Kafka 消费者或 WebSocket 监听
            // 示例：
            // kafkaTemplate.receive("business-events")
            //     .filter { it.entityId == twin.entityId }
            //     .subscribe { event ->
            //         val newState = stateManager.updateState(twin.state, event)
            //         twin.state = newState
            //         updateVisualization(twin, newState)
            //     }
            
            logger.info("Realtime sync started for ${twin.entityType}:${twin.entityId}")
        } catch (e: Exception) {
            logger.error("Failed to start realtime sync", e)
        }
    }
    
    private fun updateVisualization(twin: DigitalTwin, state: TwinState) {
        // 更新3D可视化
        try {
            // TODO: 实际应该通过 WebSocket 推送到前端进行3D渲染
            logger.debug("Updating visualization for twin ${twin.id}")
            
            // 示例：
            // websocketTemplate.convertAndSend(
            //     "/topic/twin/${twin.id}",
            //     VisualizationUpdate(
            //         twinId = twin.id,
            //         state = state,
            //         timestamp = Instant.now()
            //     )
            // )
        } catch (e: Exception) {
            logger.error("Failed to update visualization", e)
        }
    }
    
    private fun createSimulationEnvironment(scenario: SimulationScenario): SimulationEnvironment {
        return SimulationEnvironment(scenario.parameters)
    }
    
    private fun loadInitialState(scenario: SimulationScenario): SimulationState {
        return SimulationState(
            orders = emptyList(),
            inventory = emptyMap(),
            revenue = 0.0,
            costs = 0.0
        )
    }
    
    private fun calculateMetrics(state: SimulationState): Map<String, Double> {
        return mapOf(
            "order_count" to state.orders.size.toDouble(),
            "revenue" to state.revenue,
            "costs" to state.costs,
            "profit" to (state.revenue - state.costs)
        )
    }
    
    private fun analyzeSimulation(timeline: List<SimulationSnapshot>): SimulationAnalysis {
        val finalMetrics = timeline.lastOrNull()?.metrics ?: emptyMap()
        
        return SimulationAnalysis(
            finalMetrics = finalMetrics,
            summary = "Simulation completed with ${timeline.size} steps"
        )
    }
    
    private fun applyVariation(
        base: SimulationScenario,
        variation: ScenarioVariation
    ): SimulationScenario {
        return base.copy(
            parameters = base.parameters + variation.changes
        )
    }
    
    private fun compareScenarios(
        baseline: SimulationResult,
        variations: List<VariationResult>
    ): ScenarioComparison {
        return ScenarioComparison(
            baseline = baseline.analysis.finalMetrics,
            variations = variations.associate {
                it.variation.name to it.result.analysis.finalMetrics
            }
        )
    }
}

/**
 * 数字孪生体
 */
data class DigitalTwin(
    val id: String,
    val entityId: String,
    val entityType: EntityType,
    var state: TwinState,
    val config: TwinConfiguration,
    val createdAt: Instant
)

data class TwinState(
    val properties: Map<String, Any>,
    val metrics: Map<String, Double>
)

data class TwinConfiguration(
    val syncInterval: Duration = Duration.ofSeconds(1),
    val enablePrediction: Boolean = true
)

/**
 * 模拟场景
 */
data class SimulationScenario(
    val id: String,
    val name: String,
    val type: SimulationType,
    val startTime: Instant,
    val endTime: Instant,
    val timeStep: Duration,
    val parameters: Map<String, Any>
) {
    fun shouldTerminate(state: SimulationState): Boolean {
        // 实现终止条件
        return when {
            // 资源耗尽
            state.inventory.values.sum() <= 0 -> true
            // 亏损过大
            state.costs > state.revenue * 2 -> true
            // 订单满足
            parameters["targetOrders"]?.let { target ->
                state.orders.size >= (target as? Number)?.toInt() ?: Int.MAX_VALUE
            } ?: false
            // 其他条件
            else -> false
        }
    }
}

enum class SimulationType {
    ORDER_FULFILLMENT,
    INVENTORY_OPTIMIZATION,
    PRODUCTION_PLANNING,
    PEAK_SEASON,
    SUPPLY_DISRUPTION
}

data class SimulationState(
    val orders: List<Any>,
    val inventory: Map<String, Int>,
    val revenue: Double,
    val costs: Double
) {
    fun copy(): SimulationState = this.copy()
}

data class SimulationSnapshot(
    val time: Instant,
    val state: SimulationState,
    val metrics: Map<String, Double>
)

data class SimulationResult(
    val scenario: SimulationScenario,
    val timeline: List<SimulationSnapshot>,
    val analysis: SimulationAnalysis
)

data class SimulationAnalysis(
    val finalMetrics: Map<String, Double>,
    val summary: String
)

data class ScenarioVariation(
    val name: String,
    val description: String,
    val changes: Map<String, Any>
)

data class VariationResult(
    val variation: ScenarioVariation,
    val result: SimulationResult
)

data class WhatIfAnalysisResult(
    val baseline: SimulationResult,
    val variations: List<VariationResult>,
    val comparison: ScenarioComparison
)

data class ScenarioComparison(
    val baseline: Map<String, Double>,
    val variations: Map<String, Map<String, Double>>
)

data class SimulationEnvironment(
    val parameters: Map<String, Any>
)

data class StepResult(
    val newState: SimulationState
)

/**
 * 状态管理器
 */
interface StateManager {
    fun updateState(currentState: TwinState, event: BusinessEvent): TwinState
}

/**
 * 模拟引擎
 */
interface SimulationEngine {
    suspend fun simulate(twin: DigitalTwin, triggerEvent: BusinessEvent): Any
    suspend fun step(
        environment: SimulationEnvironment,
        currentState: SimulationState,
        deltaTime: Duration
    ): StepResult
}
